Ski construction

ABSTRACT

A ski construction is characterized by a longitudinally extending fiber-reinforced plastic honeycomb core having hollow tubular members and upper and lower foam-filled corrugations. Plastic sides for the ski are locked into longitudinally extending sockets along the side edges of the honeycomb core and a plastic top covers the honeycomb core. An epoxy or phenolic binder bonds a bottom running surface of the ski to the honeycomb core and the elasticity of the binder determines the dampening characteristics of the ski.

United States Patent Molnar [451 Jan. 21, 1975 SK] CONSTRUCTION [75] Inventor: Arpad A. Molnar, Boulder, C010.

[73] Assignee: Molnar & Co., Inc., Boulder, C010.

[22] Filed: July 30, 1973 [21] Appl. No.: 383,988

[52] US. Cl 280/11.l3 L [51] Int. Cl. A63c 15/00 [58] Field of Search 280/11.13 L

[56] References Cited UNITED STATES PATENTS 3,736,609 6/1973 Saucier 280/1 1.13 L

FOREIGN PATENTS OR APPLICATIONS 734,828 5/1966 Canada 280/11.13 L

1,173,199 12/1967 Great Britain 280/ll.13 L

702,418 1/1965 Canada 280/1 1.13 L

Primary ExaminerAllen N. Knowles Attorney, Agent, or Firm-Burton, Crandell &

Polumbus [57] ABSTRACT A ski construction is characterized by a longitudinally extending fiber-reinforced plastic honeycomb core having hollow tubular members and upperand lower foam-filled corrugations. Plastic sides for the ski are locked into longitudinally extending sockets along the side edges of the honeycomb core and a plastic top covers the honeycomb core. An epoxy or phenolic binder bonds a bottom running surface of the ski to the honeycomb core and the elasticity of the binder determines the dampening characteristics of the ski,

13 Claims, 7 Drawing Figures PATENTED 3.861.699

on. v

PATENTEDJAHZ] I975 sum ear 2 SKI CONSTRUCTION The present invention relates generally to board construction for recreational equipment and more particularly to a new and improved snow ski construction.

A good snow ski combines a rather delicate balance between rigidity and flexibility, while maintaining other important characteristics such as torsional response and vibration dampening. While originally, wood was the best known material for obtaining the desired characteristics, more recently, it has been found that plastic or fiber reinforced plastic can be used to obtain the desired characteristics and at the same time extend the useful life of the ski. Typical plastic or fiberglass skis, however, have required the use of continuous metal, plastic or fiber reinforced plastic strips along the top and bottom of the core of the ski in addition to the outer covering of the ski to give the desired rigidity and flexibility balance but due to metal fatigue, the life of these skis is also unnecessarily limited.

It is, therefore, an object of the present invention to provide a new and improved ski construction giving a desirable balance between rigidity and flexibility while maintaining a prolonged life of the ski.

vide a ski construction wherein the desired balance between rigidity and flexibility is obtained in the core of the ski and does not require outer strips of metal, plastic or reinforced plastic material to obtain plastic material to obtain the desired balance.

it is another object of the present invention to provide a ski construction wherein the components thereof are easily varied to obtain the desired balance between rigidity and flexibility, the desired torsional response, and the desired vibration dampening characteristics.

It is another object of the present invention to provide a ski construction having a honeycomb core defining longitudinally extending hollow tubular passages and upper and lower foam-filled corrugations which cooperate in establishing the desired balance between rigidity and flexibility of the ski as well as the torsional resistance of the ski.

It is still another object of the present invention to provide a ski construction in which a honeycomb core has sockets along opposite sides to retain sidewall elements of the ski.

These and other objects of the present invention are obtained with a simplified ski construction which has been designed so that the balance between rigidity and flexibility is variable, the dampening characteristics of the ski are variable and the torsional response of the ski is variable.

More particularly, the ski construction of the present invention has a honeycomb core defining hollow longitudinally extending tubular passages and upwardly and downwardly opening longitudinally extending corrugations with the corrugations being filled with a foam material, the elasticity of which determines the torsional response of the ski. Preferably, the honeycomb core is made of a fiber reinforced plastic material and consists of symmetrical corrugated sheets. The sheets are bonded together with an adhesive medium to establish the tubular passages and by varying the thickness of the adhesive medium, the balance between rigidity and flexibility of the ski is controlled. The running base and running edges of the ski are bonded to the core by a bonding medium, the elasticity of which determines the vibration dampening characteristics of the ski. Abrasion-resistant sides are positively locked in longitudinal sockets extending along opposite sides of the honeycomb core and an abrasion resistant top covers the top surface of the core whereby the core of the ski is completely sealed.

Other objects, advantages and capabilities of the present invention will become more apparent as the description proceeds taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of the ski construction of the present invention with parts removed for clarity,

FIG. 2 is a side elevation of a ski constructed in accordance with the present invention,

FIG. 3 is an enlarged vertical section taken along line 33 of FIG. 2,

FIG. 4 is an enlarged vertical section taken along line 44 of FIG. 2,

FIG. 5 is a vertical section taken along line 5--5 of FIG. 3,

FIG. 6 is a transverse vertical section taken through a ski incorporating a second embodiment of the present invention, and

FIG. 7 is a transverse vertical section taken through a ski incorporating a third embodiment of the present invention.

The component parts of the ski construction 10 of the present invention are probably best seen in FIG. 1 to include a honeycomb core 12, an abrasion resistant top 14, side wall elements 16, a bottom running element l8 and running edges 20 which are integrally connected in a manner to be described hereinafter to comprise a ski construction in which the desired balance between rigidity and flexibility, the desired torsional response, and the desired dampening characteristics can be obtained. As is conventional in snow ski construction, each component of the'ski is bowed in a longitudinal direction to give the ski the desired camber.

Referring first to the honeycomb core 12, as best illustrated in FIG. 3, it can be seen to define three parallel, hollow tubular elements 22 extending longitudinally of the ski with each hollow element having a hexagonal transverse cross-sectional configuration. The top and bottom walls 24 and 26 respectively of the tubular elements 22 are preferably thicker than the side walls 27 of the elements so that the hollow passages through the elements are somewhat flattened. The tubular elements 22 are connected together by horizontal planar web elements 28 which are comparable in overall thickness to the top and bottom walls of the tubular elements 22 so that upwardly and downwardly opening trough-shaped corrugations 29 of trapezoidal crosssection are established between the tubular elements. Along each longitudinal side of the core member 12, retention sockets 30 are defined by a channel which resembles a half-portion of a tubular element 22 with inturned lips 32 terminating in spaced relationship to each other so that the sockets 30 open outwardly through the side of the core member 12. The core member 12 is thicker at its longitudinal center than at opposite ends so that the top and bottom surfaces of the core member converge in a forward and rearward direction from the approximate longitudinal center of the core member whereby at the extreme leading and trailing ends, 34 and 36 respectively, of the core memher, the tubular elements 22 and corrugations 29 are eliminated. At the leading end 34, the core member arches upwardly defining the leading tip of the ski. The core 12 is preferably made of a fiber-reinforced plastic with the plastic being a resin such as epoxy, polyester or vinylester and the reinforcement fibers being fibrous glass, boron, sapphire, carbon, graphite, ceramic or combinations of these materials.

The honeycomb core 12 is preferably constructed from upper and lower identical corrugated sheets 38a and 38b which are bonded in opposed face-to-face relationship and in a symmetrical manner to establish the honeycomb construction hereinbefore described. Each sheet can be seen to have corrugations on opposite sides so that when the sheets are bonded together, the tubular elements 22 and upwardly and downwardly opening corrugations 29 of the core member 12 are established. The corrugated sheets are bonded along their interface 40 with an epoxy resin or similar bonding medium 41 and by varying the thickness of the bonding medium 41 it has been found that the balance between rigidity and flexibility desired for the ski can be varied. In other words, the greater the thickness of the bonding medium, the more rigid the ski becomes and conversely, the thinner the bonding medium, the more flexible the ski becomes.

The corrugations 29 defined between the tubular elements 22 of the core 12 which open both upwardly and downwardly, are filled with an elastic semi-flexible foam material 42 such as a synthetic polyurethane, epoxy, or syntactic foam and the elasticity of the foam will determine the torsional response of the ski. In other words, a high torsional response can be obtained with a high degree of elasticity in the foam material 42 while a lower degree of elasticity in the foam material would lessen the torsional response.

The side wall elements 16 of the ski are positively retained in the longitudinal sockets 30 along the sides of the core member 12 and are preferably made of a polyurethane, polyethylene, polysulfone, foam and/or a syntactic foam, or acrylonitrile-butadiene-styrene, commonly referred to as ABS. Any of these materials provide an abrasion resistant, water-proof external side sufrace for the ski to assure a long life. The top edges of the side wall elements 16 are flush with the top surface of the honeycomb core 12 and with the foam material 41 in the corrugations 29 of the core whereby the top surface of the core is easily covered by the top element 14 to seal the core member. The top element 14 of the ski is preferably a polyurethane lacquer but could also be a sheet of polyurethane or ABS bonded to the core to provide an abrasion-resistant, waterproof top surface for the ski.

The running edges of the ski are conventional and comprise elongated metallic strips of inverted L-shaped cross-section having a longitudinal groove 43 in the undersurface thereof adapted to receive the bottom running element 18 of the ski which fits flush with the running edges 20 to define a smooth bottom surface of the ski.

The running edges 20 and bottom running element 18 of the ski are bonded to the foam-filled core by a bonding medium 44 which fills a hollow cavity 45 defined between the bottom element, running edges and the core member. This bonding medium 44 is preferably a phenolic adhesive, a glass-reinforced epoxy or polyurethane, a polyester or polyurethane. The elasticity of the bonding medium 44 determines the dampening characteristics of the ski, or in other words, the ability of the ski to absorb vibration or chatter. Accordingly, the dampening characteristics of the ski are also variable upon construction of the ski.

The bottom running element 18 of the ski is preferably made of a high-density polyethylene material such as a material marketed under the name P-tex by lnter Montana Sports in Switzerland. As is conventional, the lower surface of the bottom running element 18 has a longitudinally extending groove 46 which enhances the tracking ability of the ski and the leading end 48 of the bottom running element 18 is curved upwardly to conform with the leading end of the core in defining the leading tip of the ski.

Along a portion of the approximate longitudinal center of the ski 10, a mounting plate 50, preferably of aluminum, FIGS. 2, 4 and 5, is inserted into recessed cavities formed in the opposing faces of the corrugated sheets 38a and 38b defining the honeycomb'core 12. The mounting plate 50 is, of course, held in place by the bonding medium 41 joining the corrugated sheets whereby it is totally integrated into the ski. The mounting plate provides a strong anchoring base for bindings 52, FIG. 2, to be-mounted on the ski whereby metal screws 54 can be used to anchor the bindings to the ski in a positive and reliable manner.

In manufacturing the ski of the present invention, the two corrugated sheets 38a and 38b would first be bonded in abutting facing relationship with the appropriate thickness of bonding material 41 to give the balance between rigidityand flexibility desired for the particular ski. Next, the corrugations 29 in the upper-and lower surfaces of the core member 12 would be filled with the foam material 42 having an elasticity dependent upon the torsional response desired for the ski. The sides 16 of the ski would then be molded or injected into the retention sockets 30 along the sides of the core member to take the desired configuration'so that the integrated foam-filled core member with the sides as a part thereof could be placed into a form or jig in which the bottom running element 18 and running edges 20 were prealigned. An excess of the bonding medium 44 would have been filled in the cavity between the bottom element and the core so that the core could be clamped against the running edges and bottom element causing the bonding medium 44 to be squeezed outwardly between the running edges and the core to positively secure the running edges as well as the bottom running element. Again, as mentioned previously, the elasticity of the bonding material 44 between the core and the bottom element determines the dampening characteristics of the ski and this too would be selected for the particular ski being manufactured. Finally, the top element 14 of the ski would be incorporated thereonto either by applying the polyurethane lacquer or by bonding the sheet of polyurethane or ABS in a conventional manner.

Referring now to FIG. 6, another embodiment S5 of the invention is illustrated wherein there are four longitudinally extending tubular elements 56 of hexagonal transverse cross-section as opposed to the three elements 22 disclosed in the first described embodiment. Otherwise, the ski disclosed in FIG. 6 would be identical to the previously described ski and it is to be understood that any number of hexagonal tubular elements could be utilized.

In FIG. 7, still another embodiment 58 of the ski construction of the present invention is shown wherein the tubular elements 60 are generally circular in crosssection with flattened top and bottom surfaces 62. The core element of this embodiment could be manufactured by an extrusion process and in addition to the two-part core illustrated, the core could be extruded in a single piece.

Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that changes in details of structure may be made without departing from the spirit thereof.

What is claimed is:

l. A recreational board construction comprising in combination:

an elongated core member including hollow tubular elements with connecting web elements retaining the tubular elements in parallel spaced relationship, elongated open corrugations between said tubular elements,

a filler material means in the open corrugations, for

controlling the torsional response of the board,

a planar bottom element, and

an adhesive bonding medium securing the bottom element to the bottom surface of the core member.

2. A ski comprising in combination:

an elongated core member including longitudinally extending hollow tubular elements with connecting web elements retaining the tubular elements in parallel spaced relationship, longitudinally extending open corrugations between the tubular elements,

a filler material means in at least one of the open corrugations for controlling the torsional response of the ski,

a bottom element extending along the length of the core member, and

means securing the bottom element to a bottom surface of the core member.

3. The ski of claim 2 wherein said core member is made of a fiber reinforced plastic material.

4. The ski of claim 3 wherein said filler material is a foam.

5. The ski of claim 4 wherein said bottom element is made of a high molecular weight polyethylene material.

6. The ski of claim 5 wherein said bonding medium is fiber reinforced.

7. The ski of claim 2 wherein said core member is comprised of a pair of corrugated sheets disposed in opposed facing relationship so as to define the longitudinally extending tubular elements and open corrugations, and further including a layer of bonding material between the corrugated sheets securing the corrugated sheets in facing relationship.

8. The ski of claim 7 wherein said core member further includes open socket portions along opposite sides thereof, and sidewall members retained in said socket portions to extend along the length of the core memher.

9. The ski of claim 8, further including a metal plate between the corrugated sheets extending along a limited portion of the length of the corrugated sheets at the approximate longitudinal center of the corrugated sheets.

10. The ski of claim 8 wherein said tubular elements are of hexagonal transverse cross-section.

11. The ski of claim 8 wherein said tubular elements are of substantially circular transverse cross-section.

12. The ski of claim 7 wherein said web elements are formed from flat web sections on each corrugated sheet and wherein the web sections are secured together by said layer of bonding material.

13. A ski construction comprising in combination:

an elongated fiber reinforced semi-rigidplastic core member having a pair of corrugated sheets disposed in opposed facing relationship and defining a plurality of longitudinally extending hollow tubular elements of hexagonal transverse cross-section with integral connecting web elements retaining the tubular elements in parallel spaced relationship and a plurality of longitudinally extending corruga-v tions between the tubular elements, the longitudinal side edges of the core member having continuous longitudinally extending sockets opening through the side of the core member,

a semi-rigid synthetic foam material in the longitudinally extending corrugations of the core member,

a high molecular weight polyethylene planar bottom element extending along the length of the core member, steel running edges extending along opposite sides of the bottom element, I

a glass reinforced bonding medium securing the bottom element and the running edges to a bottom surface of the core member,

thermal plastic sidewall members received in said longitudinally extending sockets of the core member, and

a plastic top sheet bonded to a top surface of the core member.

UNiTED STATES PATEIIT OFFKIE CERTIFECATE OF CQRREfiTION Patent No. 3 99 Dated y 30, 1973 Arpad A. Molnar Inventor(s) It is certified that error appears in the above-identified patent 'and that said Letters Patent are hereby corrected as shown below:

Column 1., line 28 and 29, delete "to obtain plastic material".

Column 3, line 43, "sufrace" should read --surface--.

Signed and sealed this 29th day of April 1975 (SEAL) Attest: v

. C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Traciemarks V 

1. A recreational board construction comprising in combination: an elongated core member including hollow tubular elements with connecting web elements retaining the tubular elements in parallel spaced relationship, elongated open corrugations between said tubular elements, a filler material means in the open corrugations, for controlling the torsional response of the board, a planar bottom element, and an adhesive bonding medium securing the bottom element to the bottom surface of the core member.
 2. A ski comprising in combination: an elongated core member including longitudinally extending hollow tubular elements with connecting web elements retaining the tubular elementS in parallel spaced relationship, longitudinally extending open corrugations between the tubular elements, a filler material means in at least one of the open corrugations for controlling the torsional response of the ski, a bottom element extending along the length of the core member, and means securing the bottom element to a bottom surface of the core member.
 3. The ski of claim 2 wherein said core member is made of a fiber reinforced plastic material.
 4. The ski of claim 3 wherein said filler material is a foam.
 5. The ski of claim 4 wherein said bottom element is made of a high molecular weight polyethylene material.
 6. The ski of claim 5 wherein said bonding medium is fiber reinforced.
 7. The ski of claim 2 wherein said core member is comprised of a pair of corrugated sheets disposed in opposed facing relationship so as to define the longitudinally extending tubular elements and open corrugations, and further including a layer of bonding material between the corrugated sheets securing the corrugated sheets in facing relationship.
 8. The ski of claim 7 wherein said core member further includes open socket portions along opposite sides thereof, and sidewall members retained in said socket portions to extend along the length of the core member.
 9. The ski of claim 8, further including a metal plate between the corrugated sheets extending along a limited portion of the length of the corrugated sheets at the approximate longitudinal center of the corrugated sheets.
 10. The ski of claim 8 wherein said tubular elements are of hexagonal transverse cross-section.
 11. The ski of claim 8 wherein said tubular elements are of substantially circular transverse cross-section.
 12. The ski of claim 7 wherein said web elements are formed from flat web sections on each corrugated sheet and wherein the web sections are secured together by said layer of bonding material.
 13. A ski construction comprising in combination: an elongated fiber reinforced semi-rigid plastic core member having a pair of corrugated sheets disposed in opposed facing relationship and defining a plurality of longitudinally extending hollow tubular elements of hexagonal transverse cross-section with integral connecting web elements retaining the tubular elements in parallel spaced relationship and a plurality of longitudinally extending corrugations between the tubular elements, the longitudinal side edges of the core member having continuous longitudinally extending sockets opening through the side of the core member, a semi-rigid synthetic foam material in the longitudinally extending corrugations of the core member, a high molecular weight polyethylene planar bottom element extending along the length of the core member, steel running edges extending along opposite sides of the bottom element, a glass reinforced bonding medium securing the bottom element and the running edges to a bottom surface of the core member, thermal plastic sidewall members received in said longitudinally extending sockets of the core member, and a plastic top sheet bonded to a top surface of the core member. 